在场景之间传送时载入动画

I am making an iOS game using Swift. At the menu (Menu is a SKScene), I have a button that starts the game, let's call it 'start button'. When I hit the start button, application freezes and loads the gameplay (gameplay is a SKScene), then transition animation runs and gameplay begins. But instead of the freeze of the application, I want a rotating loading circle while application loads the gameplay. How can I do that? Ask me if there is something not clear... I am making an iOS game using Swift. At the men